1. Field of the Invention
The present invention relates to an organic positive temperature coefficient (PTC) thermistor. More specifically, the present invention relates to an organic PTC thermistor in which a pair of electrodes are formed on one main surface of an organic PTC thermistor sheet which is covered by insulation film, each electrode has a conductive sheet laminated thereon, and a terminal is inserted so that it penetrates the insulation film, respective conductive film, the corresponding electrode, and the organic PTC thermistor sheet.
2. Description of the Prior Art
If conductive particles such as carbon black, graphite, metallic powder or the like are mixed and distributed in a polyolefin family resin such as polyethylene, the resin takes on the characteristics of a PTC thermistor. It has been known that it is possible to construct a heating plate by forming such a resin having the characteristics of a PTC thermistor into an organic PTC thermistor sheet and by forming a pair of electrodes on one main surface of the organic PTC thermistor sheet.
A configuration of one example of a conventional PTC thermistor which utilizes such an organic PTC thermistor sheet is shown in FIG. 1. More specifically, an electrode 2 is formed on an organic PTC thermistor sheet 1 and the electrode 2 and the organic PTC thermistor sheet 1 are covered by insulation film 3 and 4. Then, a terminal 5 is inserted so as to penetrate the insulation film 3, electrode 2, organic PTC thermistor sheet 1 and the insulation film 4, and crimped.
In the conventional PTC thermistor as shown in FIG. 1, when the terminal 5, is crimped the organic PTC thermistor 1 is deformed. At this time, since the electrode 2 has been formed by printing conductive paste and lacks elasticity, the electrode in the vicinity of a portion where the terminal is crimped is destroyed. Therefore, contact between the terminal 5 and the electrode 2 becomes unstable, and therefore, contact resistance becomes large. If the organic PTC thermistor is used in such a state, abnormal heat generation due to large contact resistance takes place, and therefore, the PTC thermistor is thermally destroyed.